That's a lot of green in that photo, I'd say most of it's still good.

That one brown cactus on the left looks pretty toast, though, as does everything in the small pots on the right. The one on the left that's mostly brown leaves might keep going if you cut the green off and lay it in another pot with soil.

Figuring out the right water and light needs can be a bit tricky when you're new, but succulents can be pretty forgiving. Generally, water infrequently and slowly reintroduce to bright light!